In a charge-coupled device (CCD) type or an amplification type solid-state imaging apparatus used in a digital still camera, a cam coder, etc, there is a demand for making pixels fine to obtain high definition images. However, the finer the pixels, the smaller the light receiving area of a photoelectric conversion element for detecting light contained in each pixel, resulting in deterioration in sensitivity.
Japanese Patent Application Laid-Open No. 2006-191081 discusses a complementary metal oxide semiconductor (CMOS) type, i.e., an amplification type, solid-state imaging apparatus in which, to secure the light receiving area for the photoelectric conversion element, a first substrate on which the photoelectric conversion element and a transfer transistor are arranged and a second substrate on which another circuit is arranged are bonded together to form the solid-state imaging apparatus. In the solid-state imaging apparatus as discussed in Japanese Patent Application Laid-Open No. 2006-191081, a connection portion extending through the second substrate is connected with a pad (input/output pad) to establish pad connection from the back-side face side of the second substrate. The pad is formed on the back-side face of the second substrate after exposure of a second connection portion by polishing the second substrate.
Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2010-514177 discusses a manufacturing method of an electronic component in which a first substrate equipped with an image sensor and a first conductive area and a second substrate equipped with an integrated circuit and a second conductive area are bonded to each other. After the bonding of the first substrate and the second substrate, the first conductive area and the second conductive area are exposed, and, further, a conductive layer is stacked thereon to form electrical connection between the first conductive area and the second conductive area. The first conductive area or the conductive layer is used as the pad (external connection pad).